I have a 20hp mercury on my bass tracker and it is giving me problems. I changed the plugs but the motor seems to be shaking alot. every once in a while when i give it the gas when i am traveling the motor will act like i just choked the carberator it will slow and bog down. I was thinking i just have bad gas in it.. i notice on the top of the carberator there is a small cylnder with a spring and 2 wires going to it that seem to have been burnt. i am not sure what that is. I also noticed that it seems to be smoking more this year(white smoke) i am looking for any sugestions thank you in advance!
You don't mention what model year the engine is, but it sounds like the enrichening system is open all the time allowing extra fuel to enter the cylinders all the time. That would be indicated by the constant white smoke. The "cylinder" that you describe with a spring and burned wire also leads me to believe that the choke system was stuck on at one time and burned the solenoid and wires. a job of this detail would be best performed by a dealer due to the nature of the repair and the safety issue of messing with a fuel system. Good Luck!